| 摘要 |
Disclosed is a high etch cleaner for aluminum and aluminum alloy substrates that leads to enhanced corrosion protective performance of a variety of anti-corrosion pretreatments. The cleaner comprises very low levels of silicate of from 0 to 250 ppm, 50 to 500 ppm of at least one chelator selected from EDTA or its salts, NTA or its salts, DTPA or its salts, iminodisuccinic acid or its salts, EDDS or its salts, tartaric acid or its salts, or a mixture thereof, and has a high pH of from 11.0 to 13.5. Preferably the cleaner is used to etch from 0.5 to 4.0 grams per meter squared from the substrates. Substrates treated with the cleaner and then coated with a variety of anti-corrosion pretreatments and outer coatings show enhanced corrosion resistance compared to substrates cleaned with standard cleaners that have low etch rates, high silicate levels and no chelating agents followed by anti-corrosion pretreatments and outer coatings. |
